This invention relates to mechanical apparatus for changing the speed and torque of the output shaft of a prime mover relative to its input shaft. More specifically, this invention is directed to an apparatus for providing up to an infinite number of seamless, ripple free changes of speed and torque from a power source such as a gas or diesel engine, an electric motor, a jet engine, a steam engine, the crank of a bicycle, or the like.
Historically, significant efforts have been directed to the provision of transmission assemblies adapted for changing the speed and torque of a power source. Many of these assemblies have involved the use of ratchet drives, eccentrically-oriented cam assemblies, and variable length lever arms. Representative of past efforts in this regard are the structures disclosed in the following issued patents: U.S. Pat. Nos. 629,389; 3,803,931; 4,630,830; 4,487,085; 6,068,570; 4,936,155.
For example, U.S. Pat. No. 629,389 discloses a bicycle in which it is stated, xe2x80x9cThe gear may be changed by substituting larger or smaller pulleys.xe2x80x9d Thus, one would have to get off the bike, take out his tool kit, take-off the pulleys and attach new and different pulleys to change gear ratios. Furthermore, U.S. Pat. No. 629,389 is a one speed transmission.
U.S. Pat. No. 4,936,155 discloses a transmission to provide constant power, speed changing and torque multiplication. The invention utilizes xe2x80x9ca variable throw cam and cam follower system to provide ripple free output speeds and wide ranging torques.xe2x80x9d The cam follower wheel makes point contact with said cam. With this configuration, the cam follower of the present transmission makes line contact with the cam, thus limiting torque and power capacity.
U.S. Pat. No. 3,803,931 discloses xe2x80x9ca variable speed transmission device comprises an output shaft rotated from a first eccentric member through unidirectional couplingsxe2x80x9d, thus rippled output speeds.
In U.S. Pat. No. 4,487,085, xe2x80x9cThe cam is tapered from one end to the other to permit the gear ratio of the transmission to be varied in infinite increments by adjusting the position of the cam relative to the followers.xe2x80x9d Power must pass the power through a tiny point of contact greatly limiting the power capacity of the transmission.
In U.S. Pat. No. 4,630,839, xe2x80x9cA bicycle having pivoted level pedal system (1, 2, 45) and lever arm length or gear ratio (speed) change devices (3, 4, 5, 6)xe2x80x9d is disclosed.
The device of U.S. Pat. No. 4,630,839 does not provide any means for removing ripple and, therefore, cannot provide seamless, ripple free outputs.
U.S. Pat. No. 6,068,570 utilizes eccentrics 14 and 25 which it refers to as cams. The eccentrics 14 and 25 cannot provide ripple free outputs. Furthermore, the transmission of U.S. Pat. No. 6,068,570 does not provide means to produce an infinite number of output speeds.
Thus, it would be advantageous to provide an infinitely variable torque multiplying, substantially constant power mechanical transmission that produces ripple free outputs, requires fewer components to assemble, is easier to manufacture, is adaptable to any prime mover providing ease of shifting, allows power shifting under load, can provide compression braking and can handle substantially more power and torque than prior art transmissions.
The instant invention includes an input shaft journaled in a restraining support or housing, one or more oscillators, two or more output levers driven by one or more oscillators. The output levers are coupled to one-way clutches on the output shaft. The throw on the output levers is by selection and infinitely variable in order to change the rotational speed of the output shaft.
In one embodiment the oscillators, levers and their respective fulcrum blocks may be rotatably coupled on a concentric shaft slidably splined on the input shaft for axial displacement relative to the fixed location of power take-offs.
In another embodiment the output slides are moveable and the oscillators are not axially moveable.
In all embodiments the movement of the power take-off members may be self powered and self locking.
Various oscillator configurations are contemplated, related but not limited to a slidable member on slide guides, wherein oscillators are adapted for back and forth linear displacement of a member along the length of those guides.
In other embodiments an oscillator may be a cam wherein a single cam will drive two levers.
In yet further embodiments two drive cams, 180xc2x0 apart, may drive the two power levers.
In another configuration, each cam drives its power lever while another cam is configured to keep the drive cam follower wheel in contact with the drive cam at all times.
In yet another configuration a spring is used to keep a cam or eccentric follower wheel in contact with the cam.
In another configuration a pair of rollers journaled on the power take-off ride on the lever while a spring holds the lever in contact with these rollers.
In another arrangement rack gears on the output slide drive a pinion gears integral with overrunning clutches journaled on the output shaft.
In some embodiments a single cam drives two cam followers 180xc2x0 apart kept in contact with the cam by spring forces.
Likewise, the single cam may have an inner and an outer race, with one biasing cam follower wheel riding on the outer face and another cam follower wheel riding on the inner race with two cam follower wheels journaled on each independent axle.
The instant invention may be adapted to include structures for selectively applying vector longitudinal force generated by transmission power levers directly on the cam/follower assemblies thereby power shifting the assemblies along the length of a shaft on which they are mechanically associated.
In some embodiments the instant invention may include a control slide, constrained in a groove or along guide rails attached to the transmission housing, and integral with cam follower (oscillator) slide guides and fulcrum blocks connecting rods.
In some embodiments the control slide is contoured with grooves having appositively oriented inclined planes wherein rollers biased in cages against the oppositely angled inclined planes in the grooves function as opposed linear one-way clutches to lock the control slide to the housing or to selectively bias the rollers by moving the cage one way or the other wherein the lever forces generated within the transmission may move the control slide one way or the other, thus providing power shifting and automatic clamping.
In another embodiment the one-way clutch cavities, rollers and cages may be in the power take-offs and automatically hold the power take-offs in selected positions or allow them to be moved by interior lever forces in one direction or the other on power levers.
Screw or hydraulic positioners or the like may be used to move or to hold the control slide.
One end of the cam driven lever provides zero output speed and maximum output torque. The other end of the lever, which may extend beyond the cam drive connection, provides the maximum output speed and a smaller output torque. Thus, the instant invention is an infinitely variable constant power transmission.
In another embodiment, by not including a moveable control slide, the transmission may be used as a low cost, power dense, one or two fixed speed reducer.
In yet another embodiment cam shaped links, sans cam followers, effectively remove ripple free selected output.